There are very few Hollywood film-makers who could have made Dunkirk. The cinemagoing public is not crying out for an epic war film about the desperate evacuation of Allied troops at the peak of Hitler’s hold on Europe in May and June 1940. But Christopher Nolan doesn’t make turkeys: this is the director of the Dark Knight trilogy, of brain-bamboozling sci-fi thriller Inception, and of the equally far out space adventure Interstellar. His movies make money – more than $4.2bn (£3.3bn) at the global box office – and studio Warner Bros has duly stumped up the cash for what is expected to be the most ambitious historical war movie since the glory years of Steven Spielberg and Oliver Stone. Nolan was even reportedly given $5m to spend on a vintage Nazi war plane, which he is said to have cheerfully smashed to smithereens for the film’s denouement.

Dunkirk stars a cavalcade of British and Irish talent, from Tom Hardy and Mark Rylance to Kenneth Branagh, Cillian Murphy and ... ahem ... Harry Styles from One Direction. Here are five takeaways from the first trailer proper.

The Nazis were rotters

As if it were not bad enough for the allied troops to be surrounded by the armies of the Third Reich in a small corner of northern France, the Nazi blighters are scattering leaflets highlighting the end of all hope over the once-picturesque villages and towns of Normandy, then bombing our chaps as they sit helpless on the beach awaiting rescue. Thankfully, the propaganda artists responsible have foolishly also included the gleaming shores of Albion on their nasty little map, thereby giving hope to both the poor doomed soldiers of Blighty, not to mention Nolan’s audience.

Mark Rylance is the worst possible person to be rescued by

Poor Cillian Murphy. Thrown out of a British ship, then pulled from the waters against all odds by a kindly gentleman in a tiny fishing boat. Farewell Nazi hordes, hello Blighty. We’ll be wrapped up warm in a Dover pub with a pint of something tepid by dinner time. But what’s that? Rylance is taking our hero back to France, returning him to the heart of darkness, death and destruction.

Nolan’s hardly known for his grasp of comedy, but this scene appears to be unintentionally hilarious, as if the trailer has somehow warped momentarily into the wartime gallows humour of Catch-22 or Blackadder Goes Forth. Still, at least it looks like the incomparable Murphy might be getting a proper lead part for once, after taking countless supporting roles for the British-American maestro of widescreen cinema.

Kenneth Branagh is king of exposition

In case that Nazi map hadn’t made things abundantly clear, Ken is here to illustrate exactly how near – yet horribly far – the Brits and their allies are from English soil. “You can practically see it from here,” he tells a minion, usefully. Branagh also reveals there are 400,000 men on the Dunkirk beaches awaiting rescue. Some are so shellshocked they appear to be walking into the sea to their apparent deaths.

One Direction fans might be in for a shock

There has been palpable excitement among hardcore Directioners that 22-year-old Harry Styles is making his big screen debut in Dunkirk. But if the foppish singer is being set up for Hollywood heroics, Nolan has a funny way of showing it. There’s poor Harry, apparently drowning in the English channel as Spitfires and Hurricanes battle with the Luftwaffe in the skies. This never happened to the Spice Girls.

This is Nolan’s answer to Saving Private Ryan

The combination of Nolan’s eye for extravagant spectacle, Hoyte van Hoytema’s searing cinematography and Hans Zimmer’s gloomily beguiling, gorgeously resonant and typically minimalist score suggests Dunkirk could be a homegrown answer to Spielberg’s relentlessly torrid paean to American second world war heroism, a brutally epic exploration of British pluck, duty and desperation in the face of Hitler’s ghastly might.